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Code division multiple access mobile communication system

a mobile communication system and code division technology, applied in multiplex communication, radio transmission, electrical equipment, etc., can solve the problems of large gate size and power consumption of the mf, the time required for timing synchronization becomes longer, and the time required for cell search becomes very large, so as to suppress the gate size and high speed

Inactive Publication Date: 2005-04-12
FIPA FROHWITTER INTPROP AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015]In order to conduct the cell search at high speed while suppressing the gate size and the power consumption, the spreading factor of the long code masked symbol is made smaller than spreading factors of other portions of the perch channels.
[0016]In particular, a symbol rate according to typical number of taps of the MF used in the mobile terminal is determined. For example, in the case where the spreading factor of the mask symbol is 64, timing synchronization is conducted by using a MF with 64 taps. In this case, the symbol length coincides with the number of taps of the MF. With coefficients corresponding to one symbol set in the MF intact, therefore, it is possible to conduct despreading of the received signal and conduct search of all timing instants in the 64 chip section. Without increasing the gate size and power consumption, fast cell search thus becomes possible.

Problems solved by technology

This results in a problem that the time required for timing synchronization, in turn the time required for cell search becomes longer.
However, both the gate size and power consumption of the MF become very large.

Method used

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  • Code division multiple access mobile communication system
  • Code division multiple access mobile communication system
  • Code division multiple access mobile communication system

Examples

Experimental program
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first embodiment

[0039]As a first embodiment, FIG. 3 shows a channel format and transmission power in the case where spreading factors of the CSC and GISC are made smaller (64 in the example) than those of other symbols of the perch channels, and the CSC and GISC are inserted at different timing instants. In order to prevent other ordinary symbol portions from being affected, a masked symbol section 131 is made to have 256 chips in the same way as the conventional system. The CSC and GISC may be inserted in any section of four sections (133, 134, 135 and 136) obtained by dividing the mask symbol section at intervals of 64 chips. In the case where the symbol length of the GISC becomes short and consequently the number of GISCs is not enough for the number of classes of the long code which GISCs are assigned to, it is also possible to adopt such a method that long code identification groups are sorted out according to which of the four insertion sections they are inserted. In the masked symbol section...

second embodiment

[0041]As a second embodiment, FIG. 4 shows a channel format and transmission power in the case where the spreading factors of the CSC and GISC are made sufficiently small (16 in the example) as compared with other symbols of the perch channels, and the CSC and GISC are multiplexed and transmitted. It is necessary to make transmission power P5 of the CSC and transmission power P6 of the GISC large so as to correspond to the spreading factors. If the symbol rate of channels other than perch channels is fast, then the number of perch channels which are affected by the fact that the perch channel power is increased will become large. In such a case, by multiplexing the CSC and GISC to shorten the section in which the transmission power becomes large as in the present embodiment, although the influence of the perch channels on other channels may be large, the shortening of the affecting symbol section surely causes influence as a whole to be lightened.

third embodiment

[0042]As a third embodiment, FIG. 5 shows a channel format and transmission power in the case where the spreading factors of the CSC and GISC are made sufficiently small (64 in the example) as compared with other symbols of the perch channels, and the GISC is repeated a plurality of times (three time in the example). By transmitting the GISC repetitively n times, the number of accumulation times is increased, and accordingly transmission power P8 of the GISC of one time is equal to 1 / n of transmission power P7 of the CSC. As a result, influence on other channels is suppressed.

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Abstract

In a mobile communication system using a code division multiple access (CDMA) method, spreading code detection and frame / slot timing synchronization (cell search) is conducted by using a long code masked symbol. The spreading factor of the long code masked symbol is set to a value lower than spreading factors of other ordinary symbols. As a result, it becomes possible to reduce the circuit scale and power dissipation of the mobile terminal and raise the speed of cell search.

Description

[0002]This is a continuation application of U.S. Ser. No. 09 / 257,002, filed Feb. 25, 1999, now U.S. Pat. No. 6,507,576.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]The present invention relates to a code division multiple access (CDMA) mobile communication system. In particular, the present invention relates to a cell search method using a long code masked symbol (search code) in perch channels.[0005]2. Description of the Related Art[0006]When a mobile terminal starts communication, or a mobile terminal moves from one base station area (cell) in which the mobile terminal is currently conducting communication to an adjacent cell (i.e., in the case of hand over) in CDMA mobile communication systems, it is necessary to conduct spread code detection or frame / slot timing synchronization. Such processing is called cell search.[0007]As for an example of a conventional cell search method, a method of spreading only one symbol located at the end of a slot by using a specia...

Claims

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Application Information

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IPC IPC(8): H04B1/707H04B7/26H04J13/00
CPCH04B1/7075H04B1/708H04B7/2628H04B7/2668H04W72/23
Inventor SUZUKI, MAYDOI, NOBUKAZUYANO, TAKASHI
Owner FIPA FROHWITTER INTPROP AG
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